Apparatus and Methods for Supporting Control Plane Data

Abstract

A wireless communications system supports control plane data and comprises: a first mobility management entity, MME; at least one second mobility management entity, MME; and a terminal device; wherein both the first MME and the at least one second MME are allocated to interoperate to support control plane data for the terminal device.

We claim: 
     
         1 . A wireless communications system supporting control plane data comprising:
 a first mobility management entity, MME;   at least one second mobility management entity, MME operably coupled to the first MME; and   a terminal device;   
       wherein both the first MME and the at least one second MME are allocated to support control plane data for the terminal device. 
     
     
         2 . The wireless communications system of  claim 1  wherein the at least one second MME comprises a processor arranged to monitor at least a subset of control plane data handled by the first MME. 
     
     
         3 . The wireless communications system of  claim 2  wherein the processor is arranged to modify at least a subset of control plane data to be handled by the first MME. 
     
     
         4 . The wireless communications system of  claim 2  wherein the processor is arranged to monitor control plane data passed between a serving gateway, S-GW, and the first MME. 
     
     
         5 . The wireless communications system of  claim 2  wherein the processor is arranged to monitor, in a first mode of operation control plane data passed between the terminal device and the first MME when the first MME and the at least one second MME are operably coupled and operational. 
     
     
         6 . The wireless communications system of  claim 5  wherein the processor is further arranged to terminate at least one or:
 received Non-Access Stratum, NAS, protocol messages and forward all NAS signalling to the first MME; 
 S1AP protocol messages and forward all S1AP signalling to the first MME. 
 
     
     
         7 . The wireless communications system of  claim 1  wherein the terminal device performs a dual registration to both the first MME and the at least one second MME. 
     
     
         8 . The wireless communications system of  claim 7  wherein the terminal device performs a dual registration to both the first MME and the at least one second MME by issuing a single registration request that results in context information of the terminal device being kept at both the first MME and the at least one second MME. 
     
     
         9 . The wireless communications system of  claim 1  wherein the at least one second MME comprises at least a subset of the MME functionality of the first MME. 
     
     
         10 . The wireless communications system of  claim 2  wherein the processor is arranged to build and update context information associated with the terminal device. 
     
     
         11 . The wireless communications system of  claim 10  wherein the processor is operably coupled to a memory element arranged to store the terminal device context information. 
     
     
         12 . The wireless communications system of  claim 1  wherein the at least one second MME processor monitors control plane data between the terminal device and the first MME following a receipt of a security key, K ASME , or a whole authentication vector from the first MME, such that the at least one second MME is able to use the same security association between the terminal device and the first MME. 
     
     
         13 . The wireless communications system of  claim 1  wherein the at least one second MME comprises a processor arranged to detect a communication link failure between the at least one second MME and the first MME, and in response thereto switch to a second mode of operation when the first MME and the at least one second MME are no longer operably coupled or the first MME is deemed non-operational. 
     
     
         14 . The wireless communications system of  claim 13  wherein the at least one second MME processor is arranged to both terminate and handle: NAS protocol messages, S1AP protocol messages and general packet radio service, GPRS, tunneling protocol control, GTP-c, messages via a S11 interface. 
     
     
         15 . The wireless communications system of  claim 13  wherein the at least one second MME processor is arranged to track the terminal device mobility in an evolved packet system connection management, ECM, idle mode and arrange a S1 handover in ECM connected mode of the terminal device. 
     
     
         16 . The wireless communications system of  claim 13  wherein the at least one second MME processor is arranged not to perform one or more of the following in the first mode of operation and to perform one or more of the following in the second mode of operation:
 trigger or coordinate paging with the terminal device; 
 manage an authentication, AKA, procedure with the terminal device; 
 handle a security mode command procedure with the terminal device; 
 choose a target MME when relocation is required at handover for the terminal device; 
 invoke one or more core network node selection functions; 
 manage ECM-IDLE/ECM-CONNECTED transitions of the terminal device. 
 
     
     
         17 . The wireless communications system of  claim 13  wherein the at least one second MME processor is arranged to invoke one or more core network node selection functions that operably re-couples to the first MME when a connection thereto becomes operational. 
     
     
         18 . The wireless communications system of  claim 17  wherein the at least one second MME processor triggers the terminal device to initiate a tracking area update, TAU, process to cause the terminal device context information at the at least one second MME to be transferred to the first MME, and the at least one second MME reverts to a proxy mode of operation. 
     
     
         19 . A proxy mobility management entity, MME, located in a wireless communications system that comprises an additional first MME wherein the first MME is operational and operably coupled to the proxy MME such that they are both allocated to support control plane data for the terminal device; the proxy MME comprising a processor arranged to:
 monitor and modify GTP control plane data passed between a serving gateway, S-GW, and the first MME via a S11 interface; and   monitor and modify S1AP messages from a base station;   monitor and terminate control plane data passed between the terminal device and the first MME; and in response thereto terminate received Non-Access Stratum, NAS, protocol messages and forward NAS signalling to the first MME.   
     
     
         20 . The proxy MME of  claim 19  wherein the processor monitors control plane data between the terminal device and the first MME following a receipt of a security key (K ASME ) or a whole authentication vector from the first MME, such that the processor is able to use the same security association between the terminal device and the first MME. 
     
     
         21 . The proxy MME of  claim 19  wherein the processor is further arranged to detect a communication link failure between the proxy MME and the first MME or the first MME is deemed non-operational, and in response thereto switch to a mode of operation where the proxy MME assumes responsibility for at least a subset of functions of the first MME. 
     
     
         22 . The proxy MME of  claim 19  wherein the processor is arranged to build and update context information associated with the terminal device. 
     
     
         23 . The proxy MME of  claim 21  wherein the processor is arranged not to perform one or more of the following in the first mode of operation:
 trigger or coordinate paging with the terminal device; 
 manage an authentication, AKA, procedure with the terminal device; 
 handle a security mode command procedure with the terminal device; 
 choose a target MME when relocation is required at handover for the terminal device; 
 invoke one or more core network node selection functions; 
 manage ECM-IDLE/ECM-CONNECTED transitions of the terminal device. 
 
     
     
         24 . The proxy MME of  claim 21  wherein the processor is arranged to:
 terminate and handle GTP control plane data; and 
 terminate and handle S1AP messages from a base station; 
 terminate and handle received Non-Access Stratum, NAS, protocol messages. 
 
     
     
         25 . A method of operation of a wireless communications system supporting control plane data with a terminal device using a first mobility management entity, MME, and a proxy mobility management entity, MME; the method comprising, at the proxy MME:
 monitoring and modifying GTP control plane data passed between a serving gateway, S-GW, and the first MME via a S11 interface; and   monitoring and modifying S1AP messages from a base station;   monitoring and terminating control plane data passed between the terminal device and the first MME; and in response thereto terminating received Non-Access Stratum, NAS, protocol messages and forward NAS signalling to the first MME.   
     
     
         26 . A non-transitory computer program product comprising executable program code for a wireless communications system supporting control plane data with a terminal device using a first mobility management entity, MME, and a proxy mobility management entity, MME, the executable program code operable for, when executed at the proxy MME, performing the method of  claim 25 .